Solar‐Blind Ultrathin Sn‐Doped Polycrystalline Ga2O3 UV Phototransistor for Normally Off Operation

Deep ultraviolet (DUV) photodetectors (PDs) based on ultrawide bandgap β‐Ga2O3 have great potential for aerospace, military, and civilian applications, especially because of their inherent solar blindness. An 8 nm thick Sn‐doped polycrystalline β‐Ga2O3 semiconductor is used as the channel material for a solar‐blind PD in this study. The β‐Ga2O3 channel is fully depleted by upward bending of the energy band owing to the work function difference between the highly p‐type Si (gate electrode) and β‐Ga2O3, resulting in normally off behavior with a positive threshold voltage under dark conditions. The normally off behavior is beneficial for simplicity of the gate‐driver circuitry and low power consumption under standby conditions. The fully depleted 8 nm thick polycrystalline β‐Ga2O3 exhibits high‐performance DUV detection capability of light at 215 nm: a low dark current of 29.3 pA and high photo‐to‐dark‐current ratio of ≈104 at zero gate voltage. This fully depleted n‐type β‐Ga2O3 semiconductor with a wafer‐scale substrate can expedite the realization of high‐performance and low‐power‐consumption solar‐blind PDs.